This invention is generally directed to toner and developer compositions, and more specifically, the present invention is directed to developer and toner compositions containing a polyimide-amic acid resin, and process for the preparation thereof. In embodiments, there are provided in accordance with the present invention, toner compositions comprised of polyimide-amic acid resins obtained, for example, by melt condensation process, and pigment particles comprised of, for example, carbon black, magnetites, or mixtures thereof, cyan, magenta, yellow, blue, green, red, or brown components, or mixtures thereof, thereby providing for the development and generation of black and/or colored images. In embodiments, there are provided in accordance with the present invention, polyimide-amic acid resins as illustrated by following the formula ##STR1## wherein m, n, and o represent random segments of the polyimide-amic acid resin, and more specifically, m is from about 0 to 99 mole percent of the resin; n is from about 0 to 99 mole percent of the resin; o is from about 1 to 100 mole percent of the resin; and the sum of m, n and o is equal to 100 mole percent of the resin; X is a tetrasubstituted aromatic or aliphatic moiety of from about 5 to about 36 carbon atoms for aliphatic, about 6 to about 36 for aromatic, and more specifically about 6 to about 30 for aromatic, and about 5 to about 36 for aliphatic, and R is an alkylene, alkyleneoxyalkylene, or poly(alkyleneoxy)alkylene. Examples of the tetrasubstituted aromatic moiety, X, include radicals of benzene, anthracene, biphenylene, diphenylene, phenanthracene, perylene, diphenyloxide, diphenylsulfoxide, diphenyl-hexafluoropropane, diphenylsulfone, benzophenone and the like, as illustrated by the following formulas ##STR2## wherein the dotted lines represent bonds from the radical moiety (X) to the carbonyl groups of the aforementioned polyimide-amic acid structures. Examples of the tetrasubstituted aliphatic moiety, X, include radicals of cyclohexane, cyclopentane, 3-methyl-3-cyclohexene, bicyclo- 2,2,2!octane, 4-methyl-3-cyclohexene, 1,1',2,2'-tetramethylene ethylenediamine, mixture thereof, and the like as illustrated by the formula ##STR3## wherein the dotted lines represent bonds from the radical moiety (X) to the carbonyl groups of the aforementioned polyimide-amic acid structures. The R groups of the aforementioned polyimideoamic acid include alkylene moieties of from about 2 to 25 carbon atoms, such as ethylene, 1,2-propylene, 1,3-propylene, 1,3-butylene, 1,4-butylene, pentylene, hexylene, decylene, alkyleneoxyalkylene such as ethyleneoxyethylene, propyleneoxypropylene, butyleneoxybutylene, ethyleneoxyethyleneoxyethylene, ethyleneoxyethyleneoxyethyleneoxyethylene, propyleneoxypropyleneoxypropylene, poly(alkyleneoxy)alkylene, mixtures thereof and the like.
There are also provided in accordance with the present invention polyimide-amic acid resins containing an ester moiety, such as represented by the formula ##STR4## wherein p, q, and r represent random segments of the resin, and p is from about 0 to 99 mole percent; q is from about 0 to 99 mole percent; r is from about 1 to 100 mole percent; and the sum of p, q and r is equal to 100 mole percent; X is a trisubstituted aromatic or aliphatic moiety of from about 5 to 36 carbon atoms; and more specifically, X is as indicated herein, and R is an alkylene, alkyleneoxyalkylene, or poly(alkyleneoxy)alkylene. Examples of the trisubstituted moiety, X, in the aforementioned polyimide-amic acid containing an ester group, include radicals of benzene, cyclohexane, anthracene, mixtures thereof and the like, and as illustrated, for example, by the formulas ##STR5## wherein the dotted lines represent bonds from the radical moiety to the carbonyl groups of the aforementioned structure of polyimide-amic acid resin containing ester group. The R groups of the aforementioned polyimide-amic acid containing ester group include alkylene moieties of from about 2 to about 25 carbon atoms such as ethylene, 1,2-propylene, 1,3-propylene, 1,3-butylene, 1,4-butylene, pentylene, hexylene, decylene, alkyleneoxyalkylene such as ethyleneoxyethylene, propyleneoxypropylene, butyleneoxybutylene, ethyleneoxyethyleneoxyethylene, ethyleneoxyethyleneoxyethylene-oxyethylene, propyleneoxypropyleneoxypropylene, poly(alkyleneoxy)-alkylene, mixtures thereof and the like.
Additionally, polyimide-amic acid resins containing moieties other than the aforementioned ester groups, such as for example, an imine moiety, a carbonate moiety or a thioester moiety, mixtures thereof and the like, and toners thereof are provided in embodiments of the present invention.
The polyimide-amic acid resins of the present invention, generally possess in embodiments a weight average molecular weight of from about 10,000 grams per mole to about 150,000 grams per mole, a number average molecular weight of from about 4,000 grams per mole to about 60,000 grams per mole, and a polydispersity, M.sub.w /M.sub.n, of from about 1.5 to about 3. Additionally, a higher polydispersity, such as from about 2.5 to about 12, can be obtained by branching or crosslinking the polyimide-amic acid resin. The branching or crosslinking of condensation resins is known, and can be accomplished by the incorporation of branching agents comprised of, for example, at least three functional groups such as hydroxyl, amine, anhydride, or carboxylic acid groups or mixtures thereof.
Furthermore, the aforementioned formulas of the polyimide-amic acid resin of the present invention can be depicted as zwitterionic forms, specifically segments n, o, q, and r, as illustrated, for example, by the formulas ##STR6##
The toner compositions of the present invention in embodiments possess a number of advantages including excellent deinkability, such as in aqueous conditions, wherein the pH is from about 8 to about 10, possess low fixing characteristics such as from about 120.degree. C. to about 145.degree. C., excellent blocking characteristics such as from about 45.degree. C. to about 65.degree. C., excellent nonvinyl-offset properties, and excellent low relative humidity sensitivities.
The polyimide-amic acid of the present invention can in embodiments be generated by the reaction of a dianhydride such as 5-(2,5-dioxotetrahydrol)-3-methyl-3-cyclohexene-1,2-dicarboxylic anhydride (I) or 5-(2,5-dioxotetrahydrol)-4-methyl-3-cyclohexene-1,2-dicarboxylic anhydride (II) available as B-4400 and B-5060, respectively, from Dai Nippon Ink Company, ##STR7## and an aliphatic diamine like ethylenediamine or 2-methylpentamethylenediamine available as DYTEK.TM. from E. I. DuPont, or a diamine terminated alkyleneoxyalkylene or poly(alkyleneoxy)alkylene, such as JEFFAMINES.TM. available from Texaco Chemicals as JEFFAMINE D-230.TM., D-400.TM., D-700.TM., EDR-148.TM., EDR-192.TM. and believed to be of the following formula ##STR8## wherein EDR-148.TM. n=2; R=H
EDR-192.TM. n=3; R=H PA1 D-230.TM. n=2,3; R=CH.sub.3 PA1 D-400.TM. n=5,6; R=CH.sub.3.
The aforementioned reaction of the diamine with the dianhydride generates a polyamic acid at a temperature of from about 25.degree. C. to about 140.degree. C., and preferably below 100.degree. C. in a sealed vessel. The aforementioned polyamic acid can be represented by 100 mole percent of either segment n or q of the aforementioned formulas, and on further heating above 100.degree. C., and preferably above 145.degree. C. to about 190.degree. C., the imidization occurs with the liberation (or elimination) of water as the byproduct (collected by distillation), and resulting in a polyimide-amic acid, wherein the amount of water collected is proportional by mole equivalent to the sum of the n and o segments or the q and r segments of the aforementioned formulas. The collection of water can usually be enhanced by reducing the pressure of the reaction system to below atmospheric pressure up to 0.01 atmosphere. In generating the polyimide amic acid of the present invention, generally, from about 0.05 to about 0.9 mole equivalent of water is removed. Removal of 100 percent of the theoretical equivalent amount of water will result in a polyimide resin wherein the segment m or p represents 100 mole percent of the resin, and segments n, o, q, r are 0 mole percent, and thus avoided.
The polyimide-amic acid resins exhibit in embodiments a number average molecular weight of from about 2,500 grams per mole to about 100,000 grams per mole as measured by vapor phase osmometer, have a glass transition temperature of from about 45.degree. C. to about 65.degree. C., and more preferably of from about 50.degree. C. to about 65.degree. C. as measured by the Differential Scanning Calorimeter, low fixing characteristics, such as from about 125.degree. C. to about 145.degree. C., possess excellent deinkability such as being removed from paper in aqueous conditions at a pH of from about 8 to about 10, and with low relative humidity sensitivity such as from about 1.2 to about 3.0.
In embodiments, the polyimide-amic acid has a number average molecular weight M.sub.n of from about 1,500 to 20,000, the weight average molecular weight M.sub.w of from about 2,500 to about 100,000, and a polydispersity of from about 1.5 to about 10.
In embodiments, the polyimide-amic acid, derived from a flexible segment such as an aliphatic or poly(alkyleneoxy)alkylene segment, of the present invention can be branched or crosslinked by utilizing an alkyltriamine or poly(alkyleneoxy)alkylene triamine, such as JEFFAMINE T-403.TM. available from Texaco Company, and believed to be of the formula ##STR9## wherein the summation of x, y and z is about 5.3. The amount of branching monomer utilized is of from about 0.5 to about 6 percent by weight of polyimide.
A number of toner resins are known, such as styrene acrylates, styrene methacrylates, styrene-butadiene, polyesters, polyamides, polyimides generally, polyester imides, polyester amides and polyimide imine. Polyimide resins are known as high performance materials, such as summarized and illustrated in the Encyclopedia of Polymer Science and Engineering, 2nd Edition, Volume No. 12, published by Wiley (1985). Polyamic acid resins are also mentioned in the aforementioned Encyclopedia, see pages 364 and 365, wherein the polyamic acid is prepared as intermediate resin and then cyclized by the imidization process to result into the polyimide resins.
Polyimide resins for use as toner resins are known; for instance, in U.S. Pat. No. 5,348,830, there is disclosed a liquid crystalline polyimide based toner with low fixing temperatures.
The polyimide-imine toners of U.S. Pat. No 5,409793 possess low fixing temperature and are disclosed to be deinkable in embodiments in caustic aqueous conditions of from about a pH of 10 to about a pH of 14, and wherein the toner resin is believed to be decomposed to oligomers. Also, disclosed in U.S. Pat. No. 5,348,831 is a polyester-imide based toner with low fixing temperature, broad fusing latitude, good deinkability, such as in caustic conditions of from about 10 to about 14, and excellent nonvinyl offset properties. Other polyimide or polyimide-ester based toner resins are illustrated in U.S. Pat. Nos. 5,427,882, 5,411,829, 5,413,888, 5,427,881, 5,411,831 and 5,413,889, which discloses toners displaying one or more of the toner characteristics such as low fixing temperature, broad fusing latitude, low relative humidity sensitivity, nonvinyl offset and good deinkability such as in alkaline condition of pH of from about 10 to about 14 with the use of surfactant. The disclosures of each of the aforementioned copending patent applications and patents are totally incorporated herein by reference.
Polyamic acid resins for use as toners are also illustrated in copending application U.S. Ser. No. 394,869, filed currently herewith, the disclosure of which is totally incorporated herein by reference. This aforementioned polyamic acid application discloses toner which display low fixing temperatures, broad fusing latitude, nonvinyl offset properties, and more importantly, improved deinkability characteristics such as being dissolved or removed from paper at lower pH range, such as from about 8 to 10, without surfactants or with the use of ionic salts. Some specifics of the deinking process are disclosed in copending application U.S. Ser. No. 394,990, filed currently herewith, the disclosure of which is totally incorporated herein by reference. The process of deinkability is disclosed in the copending application U.S. Ser. No. 369,630, however, the relative humidity sensitivity of the aforementioned polyamic acid toners are from about 2.2 to about 6. It is believed that the amic acid moieties enhances deinkability at lower pH, such as from about 8 to 10, but is accompanied by a higher relative humidity sensitivity.
The disclosures of each of the copending patent applications and patents mentioned herein are totally incorporated herein by reference.
To maintain the enhanced deinkability properties such as that of the aforementioned polyamic acid in aqueous environments of pH of from about 8 to 10, while improving the relative humidity sensitivity properties of from about 1.2 to 3.0, such as disclosed in the aforementioned polyimide toner resin, and maintaining the other toner properties, such as low fixing temperature, broad fusing latitude, nonvinyl offset, nonblocking characteristics, the present invention provides polyimide-amic acid based toners; that is intermediate products obtained from the synthesis of polyimide resins from the same monomers utilized in the preparation of its polyamic precursors. The polyimide-amic acid based toners of this invention in embodiments possess the desired toner characteristics as well as improved deinkability, and low relative humidity sensitivity.
There is a need for an environmentally friendly toner, which after being fused onto paper or transparency, can be removed by conventional deinking process as practiced by the paper mill industries. More specifically, there is a need for deinking xerographic images comprised of toners containing a resin and pigment by a simple and effective process, such as alkaline pH of from about 8 to about 14, and preferably from about 8 to about 11 with small amounts of, or preferably no surfactants. These and other needs are achievable with the toners and resins of the present invention in embodiments.